The efficient operation of a modern computer-controlled internal-combustion engine depends in part on the ability of the computer of the engine to control accurately the air/fuel ratio and the timing of the spark. Such accurate control requires that critical component parts of the system function at close to optimum O.E.M. values. One common hinderance to optimum operation has been the fouling of engine component parts with carbonaceous deposits.
Several years ago fouling of electronic fuel injectors in automobile engines became a serious problem. Injector cleaners were developed to give some relief to the injector fouling problem. After study of the problem by O.E.M. engineers and oil company chemists, it was concluded that possibly the most serious contributing factor to injector fouling was the presence of high levels of diolefins, sulfides and other polar compounds in gasolines. Other contributing factors included exhaust gas from exhaust-gas recirculation "EGR," positive crankcase ventilation ("PCV") gas, positioning of injectors close to the intake valves receiving hot back-soak temperatures, and location of injector spray pintles close to the outer tips of the injectors.
In answer to the problem of fuel-injector fouling, certain manufacturers of electronic fuel injectors redesigned their injectors. In addition, certain O.E.M.'s repositioned their injectors further back from the intake valves. Oil companies significantly reduced diolefins, sulfides, and other polar compounds in gasoline, and, in addition, the companies began to add alkylamine detergents to gasoline to help keep injectors clean. As a consequence, fuel injector deposit problems have been reduced significantly, although cleaning is occasionally still needed. However, deposits on other engine fuel areas remained a problem; e.g. intake valves, spark plugs, combustion chambers, and oxygen sensors.
With the passage of time, workers in the art were successful in developing several generic approaches for obviating the foregoing limitations. Briefly, these techniques included the following.
(a) A carburetor cleansing operation which involves pouring a cleaning composition directly into an open air throttle on the carburetor with the engine operating at a high rpm level. In this procedure, the cleaner employed is admixed with the fuel and the combination burned during the combustion process. As the cleaning liquid flows over the bottom of the intake runners in this operation, approximately 30% of the surfaces are cleaned. PA1 (b) An injector cleaning process involving the use of a pressurized container having contained therein an engine fuel and a cleaning agent in a ratio of about four parts fuel to one part cleanser. The pressurized container is connected to a transfer apparatus which is then adapted to the injector fuel rail of the engine. The fuel system is the disabled and the engine operated on the fuel/cleaner mixture from the pressurized container. This technique has been found to clean the fuel injector satisfactorily but does not appear effect cleansing of the intake valves or valve seats. PA1 (c) A vacuum disconnect technique which involves disconnecting a vacuum line on the air intake plenum and then connecting a rubber flex line to the vacuum outlet. Following, the other end of the flex line is inserted into a container of cleaning fluid. At that juncture, the engine is started and the vacuum used to evacuate the cleaning fluid from the container into the plenum. The cleaning fluid then follows the route of least resistance to the center of gravity down the plenum from the point of entry. Studies have revealed that some intake runners get the major portion of the cleaning fluid while others get none. A further limitation of this procedure arises in that the cleaning fluid does not come into contact with the injectors and therefore provides limited or no cleaning. PA1 (d) A commercial procedure to chemically clean mechanical and electronic fuel injectors together with upper engine components wherein chemical compositions are added to the fuel tank of a vehicle, cleansing being effected as the vehicle is operated. In the operation of such process it is common to employ 100 parts of fuel to one part of cleaning fluid. Studies of such processes have revealed that the use of high levels of polybuteneamine fuel additive result in the effective cleansing of soiled injectors. However, this has not proven effective at removing hardened carbonaceous deposits in the intake valve.
The numerous problems created by the presence of excessive carbonaceous deposits on intake valves include engine power loss, acceleration problems, higher emissions and fuel combustion, so creating a need for correction thereof. Currently, this end is effected either by removing the intake valves, cleaning them and re-installing, or by removing the air intake manifold (plenum) and installing a "walnut shell blaster" which loosens the carbonaceous deposits using a high pressure force of small walnut shell chips. Each of these procedures is labor intensive and economically unattractive. Unless the vehicle in issue is still under warranty, the owner will generally wait until the vehicle fails emission tests or the engine operation deteriorates to the point where it is malfunctioning.
Accordingly, it has been found that none of the aforementioned prior art procedures has been able to provide the simultaneous cleansing of fuel system engine components such as air intake plenums, intake runners, intake valves and valve seats, oxygen sensors and catalytic converters.
U.S. Pat. No. 4,992,187 to Adams et al. disclosed a composition for cleaning an internal combustion engine which included a five-membered heterocyclic ring compound and hydrazine. Although the composition of the patent could be effective in cleaning internal combustion engines, the composition had an undesirably high order of toxicity and was expensive. The technique of the patent generally required a skilled mechanical technician to clean the mechanical or electronic fuel injectors of an engine and an especially high level of skill to clean other upper engine fuel-system components.
U.S. Pat. No. 4,807,578 disclosed an injector cleaning system and technique. The technique required a quantity of an active injector cleaner to be blended into a larger quantity of engine fuel. The resulting blend was placed into a pressure resistant container and then pressurized with a compressed gas, such as air or nitrogen. A special adapter was used to attach the pressurized container to the fuel rail of the engine to be cleaned. In general, different engine models required different adapters. Consequently, a garage using the engine cleaning technique of the '578 patent had to stock a large number of adapters, with the number of adapters growing larger with each new vehicle model.
Although the injector cleaning system of the '578 patent can be effective in cleaning fuel injectors, there are a number of drawbacks with this system in practice. For example, because the fuel/cleaner mixture in the container is pressurized, several types of failure, although rare, present the hazard of a mechanic being sprayed with the cleaner/fuel or in the cleaner/fuel being sprayed onto a hot engine or onto painted surfaces of the vehicle, all with potentially serious consequences. Such potentially serious failures can arise if the threads of the connector connecting the aerosol unit to the adapter apparatus are stripped by over tightening; or if a regulator diaphragm of the adapter apparatus ruptures; or if a fitting between the regulator and a ball valve of the adapter apparatus breaks as a result of the stress of opening and closing the ball valve over a period of time.
In addition, if the wrong adapter in the apparatus of the '578 patent is used to attach the pressurized container containing fuel and cleaner to the fuel rail of the throttle body; or if the adapter seal leaks; or if the return fuel line plug is not sufficiently secured; of if the high pressure fuel line is not reattached to the fuel rail correctly, fuel or the cleaner/fuel mixture can drip onto a hot engine.
Moreover, if the return fuel line is not clamped closed in the technique of the '578 patent, the injector cleaner can flow back to the fuel tank, which can result in damage to an electric fuel pump. If an injector-cleaner apparatus of the patent remains attached to a fuel rail overnight or over a weekend, damage can be caused to a diaphragm in the fuel-return pressure regulator.
Heretofore, the only solvents known to produce sufficient synergistic engine-cleaning activity for heterocyclic ring compounds were highly alkaline compounds, such as alkylamines, ammonia, or hydrazine. When such alkaline compounds are blended with certain heterocyclic five-membered ring compounds, the resulting blend can be irritating to the skin. As a result, use of such engine cleaners by the general public is not recommended and even use by professionals is now being questioned.
A need exists for a safe and efficient chemical composition to clean injectors, intake valves, combustion chambers, spark plugs, oxygen sensors and other fuel/combustion components of internal combustion engines which need not be injected into the high pressure side of the fuel-system fuel rail and for an engine cleaning process which is so inherently safe that persons with little or no mechanical skill can conduct the cleaning process.
It is an object of the invention to provide a composition of low toxicity capable of efficiently cleaning internal combustion engine parts which can be introduced into the engine through the air intake system. It is a further object of the invention to provide a method of cleaning internal combustion engines which can be used safely by consumers as well as skilled automobile mechanics and which is inexpensive relative to conventional engine-cleaning techniques.
It is yet a further object of the invention to provide an engine cleaning composition that has a moderate or neutral pH and which would provide the cleaning power needed for the difficult job of cleaning carbonaceous deposits from internal engine surfaces.
It is also an object of the present invention to provide an inexpensive apparatus for cleaning injectors, air intake plenums, intake valves and valve seats, combustion chambers, oxygen sensors and catalytic converters, said apparatus having a cost less than that of a high quality screwdriver.
A still further object of the present invention is to provide a vehicle owner with a safe and simple technique coupled with a low cost apparatus that has sufficient versatility to attach to the air intake plenum of any internal combustion engine.